Got my tempest up and running... underwhelmed HELP!

Discussion in 'Archived Threads 2001-2004' started by Darren_T, Jul 11, 2002.

  1. Darren_T

    Darren_T Second Unit

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    I think I must have done something wrong. I hooked the sub up with great anticipation. Set my sub level to 0 on the receiver. I adjusted the volume half way up on the sub amp and bypassed the built in crossover. Left the phase at 0. When I started playing some music ( Megadeath [​IMG] ) I slowly turned up the volume on the receiver and not to far into it the sub over-extended so I turned it back down promptly. I then turned the amp gain to 1/4 where it stays now. My Velodyne CT 100 10" sub seems to perform on par with this monster.
    Can someone give me some troubleshooting tips? I'm using the LFE input BTW.
    I know something must be wrong because this thing should really scream. I built the Adire Alignment Vented Tempest with slight modifications to the dimensions but made darn sure I kept 214L volume. I also stuffed with the recommended 64 ounces of Polyfil. I only put it in two chambers since I had plenty of space to put it.
    Why is this thing extending beyond its maximum at just over 1/4 of the gain on the amp? Oh I'm using the PE 250W amp with no boost. Also, I don't seem to be getting the low frequency extension I got with my velodyne either. I tested the Matrix and when Neo gets thrown up against the subway walls in his fight I can feel the impact with the 10 more than I can hear it but with the Tempest I don't even feel it.
    HELP!!!
    Darren
     
  2. Brian Fellmeth

    Brian Fellmeth Supporting Actor

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    Any chance the voice coils are wired in opposite phase ? See what happens with just one VC wired up and the other one open.
     
  3. Jason Hammerly

    Jason Hammerly Supporting Actor

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    Did you calibrate the sub with your system? What kind of receiver do you have. Is there a limiter on your LFE channel? Are you sure you have the sub wired correctly?
     
  4. Darren_T

    Darren_T Second Unit

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    I have an Onkyo TX DS 777 and it does have a bass limiter. I set it right after the slight incident. The driver is fine no harm done. I hooked the voice coils positive to positive and negative to negative and then hooked the red wire to one positive from the amp and the black to the negative. I won't have time to double check it tonight but will have plenty of time tomorrow after work to check everything.

    I calibrated the sub. I adjusted it to 75db at reference level along with the rest of the speakers. I had to adjust the receiver sub level down a few decibles to get it at 75db with about 1/4 gain on the sub amp.

    I don't have an Avia disc yet so I haven't been able to calibrate beyond the basics. I thought it would blow my Velodyne away from the get go but there has to be something wrong because that didn't happen. Could it be that I'm too used to boomy bass from that sub? Nah, even so I think the Tempest would still perform better than what is happening with mine. I'm sure with everyone's help I can get it nailed tomorrow.

    Darren
     
  5. Dustin B

    Dustin B Producer

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    Something is definately wrong. A CT100 won't be much better than the PDR10 I had before my Tempest. And there is absolutely no comparison between the PDR10 and Tempest. My Tempest had candle sticks on a coffee table that was in the room above the one the sub was in literally dancing around when I had it turned up too much.
     
  6. Patrick Sun

    Patrick Sun Moderator
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    Have you tried flipping the phase/polarity of the connection to the driver (either by using the phase dial on the amp, or just reversing the positive/negative hookup to the driver)?
     
  7. Kerry Hackney

    Kerry Hackney Stunt Coordinator

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    Also, is it possible that you have any air leaks in the cabinet? If your tuning is in effect too high the driver will unload and easily head for the xmax limit. The last possibility is that there is some mechanical problem with that particular driver. After you've double checked everything else, contact DanW and see what the options are. A healthy Tempest should not have any problems providing the bass you want. Music should not be any problem at extreme SPL output.
     
  8. Darren_T

    Darren_T Second Unit

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    Ok, here is some more info.

    I did have one hole in the enclosure, it was one of the driver mount bolts that I forgot to put in about a 1/4" hole. I also cut the center tube of the ports to 11"...is the TOTAL length supposed to be 11" or just the center tube? I couldn't figure that out. Could a small hole like the missing screw be that big a problem on a ported sub? I haven't had a chance to test it after discovering that.

    Any help is great. I know we'll get it licked. Also, I got some advice that if nothing else is wrong with the sub I should try cutting the ports down a bit more than what was speced. I will do that if nothing else works.

    I also played with the polarity on the amp and it didn't really do much.

    Darren
     
  9. Kyle Richardson

    Kyle Richardson Screenwriter

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    Darren,
    The center tubes should be 11" so yours are correct so don't adjust their length. Do you have another amplifier to test with the sub? If so try that to eliminate the amp as being the problem. Any leaks can definitely mess up a sub's performance and will let the driver unload much easier at a much lower SPL level than a properly sealed enclosure.
    Try sealing the hole first and while you are at it you may want to double/triple check to make sure there are no other leaks...that includes around the driver and ports too. If it still has problems let me know.
     
  10. Darren_T

    Darren_T Second Unit

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    Ok, when I get home this afternoon I'll pull the driver out and double check all the wiring. I'll also go over the enclosure with a fine tooth comb but I used caulk to seal it inside after gluing my panels up. My joints were air tight to begin with so I'm sure the enclosure is sound. I'll check around the ports and make sure all my bolts are installed. I have the amp from my Velodyne so if all else fails I can remove that and hook it up to the sub if I can find a way of doing that without compromising the enclosure.

    Could packing the polyfill too tight be part of the problem? I didn't cram it in but I did put it all in two of the four chambers that have the ports... I don't think it's too tight but it isn't just layed in there either.

    Darren
     
  11. Dustin B

    Dustin B Producer

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    Is there polyfil infront of the port openings inside the box? You don't want the polyfill impeding port air flow, just making the enclosure look bigger.

    Are you useing some closed cell foam weather stripping to seal the driver to the enclosure?
     
  12. Darren_T

    Darren_T Second Unit

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    I have the majority of the polyfil below the port opening inside the box but did put some above it losely...it's the sheet kind. I will remove that and put it elsewhere as well making sure none is near the opening of the port. You are gonna think I'm stupid but I didn't use weather stripping around the driver yet because I was just testing it. I figured there wouldn't be enough leakage to cause significant problems for the test but I may be wrong eh :b

    I'm gonna seal everything up tight as can be and double check all my connections and give it another test run. What kind of pressure/flow should be coming out the ports? I could feel a little air flow but not much. The polyfil is in front of the port but it isn't packed in front of it...just losely layed over it. I would think if the ports were blocked it would be harder to reach the xmax but my logic may be flawed.

    Darren
     
  13. Dustin B

    Dustin B Producer

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    You need to get something around the basket of the driver to seal it in (that and the missing bolt will be a definate problem). Just drop by your hardware store and pick up some closed sell foam weather stripping tape. Apply it to the basket and install. Creates an excellent seal, doesn't make it impossible to get the driver out (a little difficult but not bad). It also does nothing to the enclosure and can easily be peeled off the driver.
     
  14. Darren_T

    Darren_T Second Unit

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    Ok, I'll pick some up at lunch. I had every intention of using the closed cell foam tape when I was sure the enclosure was good but I guess it is more important than I had anticipated. I sure hope that and the hole are the problem but it's hard to believe that alone will double or quadrouple the performance of the sub. Hoping so though.

    Darren
     
  15. Kerry Hackney

    Kerry Hackney Stunt Coordinator

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    Also, double check the seal around the terminal cup. I have used FrostKing brand rope caulk for building speakers. It provides a great seal but can be hard to get apart if you decide to remove a driver for some reason. Air leaks can deffinately cause big problems.

    With my Adire alignment I don't get air movement that would blow things around. That is one reason to have plenty of port area so there isn't air noise. Keep in mind too that the the air in the port is designed to move almost like a piston in a cylinder. Well designed enclosures won't replace the ceiling fan in your room.
     
  16. Mike Likens

    Mike Likens Stunt Coordinator

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    Darren, I had a similar experience with my Shiva and the PE 250 amp. Recalibrate your bass peak limiter on your processor/receiver. If set too high the PE 250 amp will overload and cause your driver to distort. I had to adjust mine from a -25 to -45 to prevent overload. I also cannot turn the volume past the halfway mark without distortion. I built the 85L vented Adire Alignment.
     
  17. Fred Seger

    Fred Seger Stunt Coordinator

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    Try turning the gain up on the amp and turning down your receiver level.
     

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